Three-Nucleon Continuum by means of the Hyperspherical Adiabatic Method

This paper investigates the possible use of the Hyperspherical Adiabatic basis in the description of scattering states of a three-body system. In particular, we analyze a 1+2 collision process below the three-body breakup. The convergence patterns for the observables of interest are analyzed by comparison to a unitary equivalent Hyperspherical Harmonic expansion. Furthermore, we compare and discuss two different possible choices for describing the asymptotic configurations of the system, related to the use of Jacobi or hyperspherical coordinates. In order to illustrate the difficulties and advantages of the approach two simple numerical applications are shown in the case of neutron-deuteron scattering at low energies using s-wave interactions. We found that the optimization driven by the Hyperspherical Adiabatic basis is not as efficient for scattering states as in bound state applications.Comment: 29 pages, 5 figures, accepted for publication in Few-Body Systems (in press

The baryonic Y-shape confining potential energy and its approximants

We discuss the validity of replacing the complicated three-body confinement operator of the Y string junction type by three kinds of approximation which are numerically much simpler to handle: a one-body operator with the junction point at the centre of mass, a two-body operator corresponding to half the perimeter of the triangle formed by the three particles, and the average of both. Two different approaches for testing the quality of the approximations are proposed: a geometrical treatment based on the comparison of the potential energy strengths for the various inter quark distances, and a dynamical treatment based on the comparison of the corresponding effective string tensions using a hyperspherical approach. Both procedures give very similar results. It is shown how to simulate the genuine string junction operator by the approximations proposed above. Exact three-body calculations are presented in order to compare quantitatively the various approximations and to confirm our analysis.Comment: 28 pages, 5 figures, submitted to EPJ

The doubly heavy baryons

We present the results for the masses of the doubly heavy baryons $\Xi_{QQ'}$ and $\Omega_{Q'Q}$ where $Q,Q'=b,c$ obtained in the framework of the simple approximation within the nonperturbative string approach.Comment: 4 pages, 1 EPS fig., using espcrc2.sty package. Talk presented by I.M.Narodetskii at the 5th International Conference on Hyperon, Charm and Beauty Hadrons, Vancouver, Canada, June 200

Nuclear Fusion via Triple Collisions in Solar Plasma

We consider several nuclear fusion reactions that take place at the center of the sun, which are omitted in the standard pp-chain model. More specifically the reaction rates of the nonradiative production of ^3He, ^7Be, and ^8B nuclei in triple collisions involving electrons are estimated within the framework of the adiabatic approximation. These rates are compared with those of the corresponding binary fusion reactions.Comment: 3 pages, latex (RevTex), no figure

About the stability of the dodecatoplet

A new investigation is done of the possibility of binding the "dodecatoplet", a system of six top quarks and six top antiquarks, using the Yukawa potential mediated by Higgs exchange. A simple variational method gives a upper bound close to that recently estimated in a mean-field calculation. It is supplemented by a lower bound provided by identities among the Hamiltonians describing the system and its subsystems.Comment: 5 pages, two figures merged, refs. added, typos correcte

Non-perturbative Gluons and Pseudoscalar Mesons in Baryon Spectroscopy

We study baryon spectroscopy including the effects of pseudoscalar meson exchange and one gluon exchange potentials between quarks, governed by $\alpha_s$. The non-perturbative, hyperspherical method calculations show that one can obtain a good description of the data by using a quark-meson coupling constant that is compatible with the measured pion-nucleon coupling constant, and a reasonably small value of $\alpha_s$.Comment: 12 pages; Submitted to Phys. Rev. C. Rapid Communication

Hyperspherical Description of the Degenerate Fermi Gas: S-wave Interactions

We present a unique theoretical description of the physics of the spherically trapped $N$-atom degenerate Fermi gas (DFG) at zero temperature based on an ordinary Schr\"{o}dinger equation with a microscopic, two body interaction potential. With a careful choice of coordinates and a variational wavefunction, the many body Schr\"{o}dinger equation can be accurately described by a \emph{linear}, one dimensional effective Schr\"{o}dinger equation in a single collective coordinate, the rms radius of the gas. Comparisons of the energy, rms radius and peak density of ground state energy are made to those predicted by Hartree-Fock (HF). Also the lowest radial excitation frequency (the breathing mode frequency) agrees with a sum rule calculation, but deviates from a HF prediction

Universality of Regge and vibrational trajectories in a semiclassical model

The orbital and radial excitations of light-light mesons are studied in the framework of the dominantly orbital state description. The equation of motion is characterized by a relativistic kinematics supplemented by the usual funnel potential with a mixed scalar and vector confinement. The influence of finite quark masses and potential parameters on Regge and vibrational trajectories is discussed. The case of heavy-light mesons is also presented.Comment: 12 page